Pengxiang Xu

Copper-Catalyzed Aerobic Oxidative Coupling of Terminal Alkynes with H-Phosphonates Leading to Alkynylphosphonates

Copper catalyzed the aerobic oxidative coupling of terminal alkynes with H-phosphonates to afford alkynylphosphonates in high yields.

Nickel-Catalyzed Cross-Coupling of Aryl Phosphates with Arylboronic Acids

The Suzuki-Miyaura cross-coupling of aryl phosphates using Ni(PCy(3))(2)Cl(2) as an inexpensive, bench-stable catalyst is described. Broad substrate scope and high efficiency are demonstrated by the syntheses of more than 40 biaryls and by constructing complex organic molecules. The poor reactivity of aryl phosphates relative to aryl halides is successfully employed to construct polyarenes by selective cross-coupling using Pd and Ni catalysts.

Nickel-Catalyzed Decarboxylative C-P Cross-Coupling of Alkenyl Acids with P(O)H Compounds.

The first nickel-catalyzed decarboxylative C-P coupling of a wide range of alkenyl acids with various P(O)H compounds, especially for H-phosphonates, has been developed, affording a versatile and efficient tool for the preparation of valuable (E)-1-alkenylphosphonates, (E)-1-alkenylphosphinate oxides, and (E)-1-alkenylphosphine oxides with high stereoselectivity and broad substrate applicability. DFT calculation revealed that the phosphine ligand exhibits better catalytic performance than the nitrogen ligand in the reductive elimination step owing to the stronger nucleophilicity and larger size.

Palladium-catalyzed Suzuki cross-coupling of arylhydrazines via C-N bond cleavage.

The first example of Pd-catalyzed Suzuki cross-coupling of readily available arylhydrazines with arylboronic acids via C-N bond cleavage was developed under air, affording various biaryl compounds with broad substrate applicability and moderate to good yields. Moreover, the rigorous exclusion of air/moisture is not required in these transformations. Thus, the protocol represents a simple and efficient procedure to access biaryl compounds.

Silver-Catalyzed, Aldehyde-Induced α-C–H Functionalization of Tetrahydroisoquinolines with Concurrent C–P Bond Formation/N-Alkylation

The first facile and efficient silver-catalyzed, aldehyde-induced three-component reaction of N-unprotected tetrahydroisoquinolines, aldehydes, and dialkyl phosphonates has been developed, providing a general one-step approach to structurally diverse C1-phosphonylated THIQs accompanied by concurrent C-P bond formation/N-alkylation with remarkable functional group tolerance and excellent regioselectivity for endo products.

Chiral phosphoproline-catalyzed asymmetric Michael addition of ketones to nitroolefins: an experimental and theoretical study

A novel pyrrolidine-based chiral phosphoproline is an effective bifunctional organocatalyst for the asymmetric Michael addition of ketones to nitroolefins giving high levels of diastereo- and enantio-selectivities (up to > 99 : 1 dr and 96% ee). anti-SR Transition state has the lowest barrier which controls the stereoselectivity, in agreement with experimental results.

α-Amino acid behaves differently from β- or γ-amino acids as treated by trimetaphosphate

Summary.The condensation reactions of sodium trimetaphosphate with single amino acids, namely glycine, L-alanine, β-alanine and γ-aminobutyric acid or pairs of these amino acids were reinvestigated by electrospray ion-trap mass spectrometry and high performance liquid chromatography. It was found when mixtures were treated by sodium trimetaphosphate only in the presence of α-amino acid dipeptides were formed. Without addition of α-amino acids, the β-amino acid or γ-aminobutyric acid could not form peptide either by themselves or with their mixtures under the same conditions. From the data it is concluded that phosphate might select α-amino acids to produce the peptides being important precursors for the origin of life.

Chirality at phosphorus in pentacoordinate spirophosphoranes: stereochemistry by X-ray structure and spectroscopic analysis

Two pairs of enantiomers of stable chiral pentacoordinate spirophosphoranes with two bonds from the amino and two bonds from the carboxyl groups of amino acids have been synthesized and analysed. The results show that differences in chirality at phosphorus are linked to distinct differences in physical properties.

N -phosphoryl amino acid models for P-N bonds in prebiotic chemical evolution

Post-translational modification of proteins by N-phosphorylation of the basic amino acid residues plays important roles in biological processes. The high-energy P-N bond might have contributed to the evolution of prebiotic chemistry. N-phosphoryl amino acids (PAAs) can serve as interesting small molecular models for the study of P-N bonds in prebiotic chemical evolution. PAAs are capable of simultaneously producing several important biomolecules such as polypeptides and oligonucleotides under mild reaction conditions. In this review, we describe the chemistry of PAAs, discusse their likely prebiotic origins and their reactivity and how they relate to biological P-N bond species. We also depict a possible prebiotic scenario mediated by PAAs in which PAAs may have acted as one of the essential forces driving prebiotic biomolecules to the first protocell.

Nickel-catalyzed one-pot tandem 1,4-1,2-addition of P(O)H compounds to 1,10-phenanthrolines.

A novel and efficient nickel-catalyzed tandem 1,4-1,2-addition of P(O)H compounds to 1,10-phenanthrolines forming various 2,4-diphosphono-1,2,3,4-tetrahydro-1,10-phenanthrolines has been developed. This reaction breaks up the aromatic stabilization and directly introduces two phosphorus moieties in one single step. This finding is the first example of transition-metal-catalyzed double hydrophosphonylation of 1,10-phenanthrolines.